If your Hearing Care Professional has recommended a directional microphone, it is possible to choose from a variety of custom models with directional microphones and receive the proven benefit of improved speech understanding in background noise. Advances in the design and manufacturing techniques of hearing aids now allow directional microphones to be placed on a variety of custom hearing aids including In-the-Ear, Half Shell, and In-the-Canal models, in addition to most Behind-the-Ear models. The DI (Directivity Index) of most of these current directional microphones is between 4 and 4-5 dB. Only two BTEs currently on the market offer three directional microphones, providing a DI of 6.5 dB. Due to space limitations, directional microphones are not available on Completely-in-the-Canal models.